JP5320414B2 - Fuel cell system - Google Patents

Abstract

A fuel cell system includes a fuel cell (1), an evaporating portion (2), a reforming portion (3), a tank (4), a heating portion (40), a water supply passage (8), a water supply source (80) being switchable between a normal mode in which water in the tank is sent to the evaporating portion by a first rotation, and a reverse mode in which the water in the water supply passage is returned to the tank by a second rotation, and a control portion (100) performing a freeze restraining process by controlling the water supply source to alternately operate in the normal mode and the reverse mode in a case where the control portion determines a possibility of a freezing or a start of the freezing of at least one of the water supply passage and the water supply source.

Description

  The present invention relates to a fuel cell system having a tank for storing raw water serving as steam for reforming.

  Patent Document 1 discloses a technique for preventing the pipe from freezing by flowing warm circulating water from a hot water tank near the pipe that is likely to freeze when the pipe in the fuel cell body is likely to freeze. In Patent Document 2, when the reforming water pipe is likely to freeze during the operation of the fuel cell, the temperature of the reforming water is adjusted by putting warm circulating water from the hot water storage tank into the water tank via the water treatment device. And a technology for preventing the freezing of the reforming water piping. In Patent Document 3, when the temperature inside the fuel cell body is low, the temperature inside the housing is increased by operating the antifreezing heater and the ventilation fan in the fuel cell body so that the internal piping does not freeze. Discloses technology to prevent freezing.

JP 2003-282105 A JP 2008-243590 A JP 2005-259494 A

  In Patent Document 1, there is a problem that the amount of heat of hot water stored in the hot water storage tank is excessively used and the exhaust heat recovery efficiency in the hot water storage tank is lowered. In patent document 2, since warm water from a hot water storage tank is introduced into a water tank, there is a problem that exhaust heat recovery efficiency in the hot water storage tank is similarly reduced. Furthermore, there is a problem that the life of the water purifier storing the reformed water is shortened. Further, there is a problem that the reforming water piping cannot be prevented from being frozen while the fuel cell system is stopped. In Patent Document 3, although the temperature inside the housing is raised, prevention of freezing of the piping is not always sufficient.

  The present invention has been made in view of the above-described circumstances, and in the winter season or cold districts, without using hot water in a hot water storage tank, water supply that connects a tank for storing raw water that becomes steam for reforming and an evaporation section It is an object of the present invention to provide a fuel cell system that is more advantageous for suppressing freezing in a passage.

  A fuel cell system according to the present invention includes: (i) a fuel cell that is supplied with an anode fluid and a cathode fluid to generate power; (ii) an evaporation unit that evaporates raw water to generate water vapor; and (iii) an evaporation unit. A reforming unit that reforms the fuel using the generated water vapor to form an anode fluid, (iv) a tank that stores raw water supplied to the evaporation unit, and (v) raw water supplied to the tank or A heating unit for heating the raw material water stored in the tank; (vi) a water supply passage for connecting the tank and the evaporation unit to supply the raw material water in the tank toward the inlet port of the evaporation unit; and (vii) a water supply A water transport source provided in the passage and capable of switching between a normal mode in which water in the tank is transported to the evaporation section by forward rotation and a reverse mode in which water in the water supply passage is returned into the tank by reverse rotation; (viii) water transport source Control And (ix) a temperature sensor for detecting environmental temperature, and (x) the control unit may cause freezing in at least one of the water supply passage and the water conveyance source. Or when freezing is started, a freezing suppression process is performed in which the forward mode and the reverse mode of the water conveyance source are alternately executed, and the raw water in the tank is reciprocated in the water supply passage to suppress freezing of the water supply passage. Run.

  According to the fuel cell system of the present invention, when there is a risk of freezing in at least one of the water supply passage and the water transport source in winter or in a cold region, or when freezing is started, control is performed. The unit executes a freezing suppression process that alternately drives the water conveyance source in the normal mode and the reverse mode. As a result, the liquid-phase raw water maintained at a temperature higher than the freezing temperature in the tank is reciprocated in the water supply passage to suppress freezing of the water supply passage. In addition, according to the condition of the raw material water in a water supply channel | path, you may carry out in order of normal mode-> reverse mode, and may be in order of reverse mode-> normal mode.

  According to the present invention, when there is a risk of freezing in at least one of the water supply passage and the water transport source in winter or in a cold region, or when freezing is started, the temperature is equal to or higher than the freezing temperature in the tank. The liquid phase raw water maintained in the reciprocating manner can be reciprocated in the water supply passage to suppress freezing of the water supply passage. Therefore, the fuel cell system can be easily activated and operated even in winter or in cold regions. According to the present invention, it is not necessary to use the hot water in the hot water tank, so that the exhaust heat efficiency of the hot water tank can be maintained high.

1 is a diagram illustrating a fuel cell system according to Embodiment 1. FIG. It is a flowchart of the freezing suppression process which concerns on other embodiment and a control part performs. It is a flowchart in the positive mode of the freeze suppression process which concerns on another embodiment and the control part performs. 10 is a flowchart in a positive mode of a freeze suppression process executed by a control unit according to still another embodiment.

  According to the present invention, the control unit executes the freeze suppression process in which the water conveyance source is alternately executed in the normal mode and the reverse mode when freezing may occur in at least one of the water supply passage and the water conveyance source. To do. Thus, raw water having a temperature higher than the freezing temperature stored in the tank (hereinafter also referred to as water) is reciprocated in the water supply passage to suppress freezing of the water supply passage. When the amount of water present in the water supply passage is large, it can be executed in the order of reverse mode → normal mode → reverse mode. When the amount of water present in the water supply passage is small, it can be executed in the order of reverse mode → normal mode → reverse mode, etc., or can be executed in the order of normal mode → reverse mode → normal mode. When there is no water in the water supply passage, the normal mode, reverse mode, normal mode, reverse mode, etc. can be executed in this order.

  According to a preferred embodiment, the control unit prioritizes the reverse mode over the normal mode at the start of the freezing suppression process, and drives the water conveyance source as the reverse mode, thereby emptying the water in the water supply passage to the tank. Execute the return processing to return to the inside. In this case, since the water in the water supply passage becomes empty, the reference state of the water supply passage is ensured. Here, the passage length and passage volume of the water supply passage are known, and the amount of water transport per unit time of the water transport source is also known. For this reason, the total flow rate of the water supplied into the water supply passage is obtained with respect to the reference state (the state where the water in the water supply passage is empty). As a result, the level of the water supplied into the water supply passage is determined, and as a result, the region where the antifreezing process is performed in the water supply passage is determined.

  According to a preferred embodiment, when the control unit determines that freezing has occurred in the water supply passage, the control unit increases the amount of heat generated per unit time of the heating unit and raises the temperature of the raw water in the tank. When the positive mode is executed next time, the heated raw material water can be supplied to the water supply passage.

  A temperature sensor is provided for detecting the environmental temperature of the system. The environmental temperature may be a temperature at a place where the system is installed or may be an internal temperature of the system casing. According to a preferred embodiment, when the temperature detected by the temperature sensor is equal to or lower than the first threshold temperature T1 (temperature considering freezing, T1 ≦ 5 ° C.), there is a considerable risk of freezing. By driving the source in the reverse mode, the water in the water supply passage can be reduced or emptied and returned to the tank. In consideration of the installation location of the system such as easy blowing of wind, etc., 1 ° C., 3 ° C., 5 ° C., etc. can be selected as T1, but it is not limited to these. Note that the first threshold temperature T1 can be lowered in places where strong winds blow.

  Further, when the temperature detected by the temperature sensor is equal to or lower than the second threshold temperature T2 (T2 <T1), the control unit determines that there is a possibility of freezing. Accordingly, it is preferable that the control unit execute a freeze suppression process in which the water conveyance source is alternately executed in the normal mode and the reverse mode, and water in the tank is reciprocated in the water supply passage to suppress freezing of the water supply passage. Examples of the environmental temperature include the outside air temperature and the temperature inside the housing of the fuel cell system (for example, the inlet side of the housing).

  According to a preferred embodiment, a water sensor is provided for detecting the presence of water in a passage portion between the evaporation section and the water conveyance source in the water supply passage. In this case, it is preferable that the control unit stops the normal mode of the water conveyance source based on a signal from the water sensor when driving the water conveyance source. When the water sensor detects water, the water has reached just before the evaporation section. For this reason, it is preferable to stop the positive mode in order to suppress the entry of water into the evaporation section. Any water sensor may be used as long as it can detect the presence of water in the passage portion, and examples thereof include a capacitance sensor, an electric resistance sensor, a weight sensor, and a water head pressure sensor.

  According to a preferred embodiment, when the water conveyance source is driven in the normal mode, the control unit switches from the normal mode of the water conveyance source to the reverse mode based on the drive time of the water conveyance source or the drive amount of the water conveyance source. In this case, it is avoided that the water in the tank is excessively supplied to the water supply passage, and the water is prevented from entering the evaporation section. The driving time or driving amount of the water conveyance source basically corresponds to the flow rate of water supplied from the water in the tank to the water supply passage. For this reason, the water level of the water supplied to the water supply passage from the reference state of the water supply passage is grasped. As a result, the area | region which can suppress freezing with water among water supply passages is grasped | ascertained.

  According to a preferred embodiment, the motor is a stepping motor. In this case, when completing the positive mode once, the total number of pulses fed to the stepping motor is Na. Alternatively, when the positive mode is completed once, the driving time for driving the stepping motor is ta. Here, the total number Na of pulses fed to the stepping motor and the driving time ta of the stepping motor are such that when the water in the water supply passage is empty (reference state), the stepping motor rotates forward and the pump is driven in the positive mode. At this time, it is preferable that the water flowing in the water supply passage toward the evaporation section can reach the height position of the water sensor (just before the inlet port of the evaporation section in the water supply passage).

  In this case, the water in the water supply passage starts from an empty state (reference state), and before the total number of pulses fed to the stepping motor reaches Na or before the driving time of the stepping motor reaches ta. When the sensor detects water, it is determined that the inner wall surface of the water supply passage is frozen and the flow passage cross-sectional area of the water supply passage is small. Therefore, the control unit preferably increases the amount of heat generated per unit time of the heating unit by ΔW from the initial stage. In this case, when the next normal mode is executed, the temperature of the water supplied to the water supply passage can be raised to improve the freeze prevention. Regarding the rotation speed of the motor (stepping motor) in the freeze suppression process, Va = Vc, Va≈Vc, Va <Vc, Va>, where Va is the rotation speed in the normal mode and Vc is the rotation speed in the reverse mode. Any of Vc may be used. Further, when the control unit determines that the water supply passage is frozen, the control unit repeatedly executes the normal mode and the reverse mode a plurality of times, and the heating unit generates heat per unit time as the number of executions of the normal mode increases. It is preferable to raise the temperature of the raw material water in the tank by increasing the amount stepwise or continuously from the initial stage. Since the temperature of the raw material water in the tank is increased as the number of executions of the normal mode increases, it is advantageous for freezing release.

[Embodiment 1]
FIG. 1 shows the concept of the first embodiment. As shown in FIG. 1, the fuel cell system reforms fuel using a fuel cell 1, an evaporation unit 2 that evaporates liquid-phase water to generate water vapor, and water vapor generated by the evaporation unit 2. The reforming unit 3 for forming an anode fluid, the tank 4 for storing liquid-phase water supplied to the evaporation unit 2, and the case 5 for storing them. The fuel cell 1 includes an anode 10 and a cathode 11 that sandwich an ion conductor, and for example, a solid oxide fuel cell (operating temperature: 400 ° C. or higher), which is also called SOFC, can be applied. The reforming unit 3 is formed by supporting a reforming catalyst on a carrier such as ceramics, is adjacent to the evaporation unit 2, and includes a temperature sensor 33. The reforming unit 3 and the evaporation unit 2 constitute a reformer 2A and are surrounded by a heat insulating wall 19 together with the fuel cell 1 to form a power generation module 18. A combustion unit 105 having an ignition unit 35 is provided between the reforming unit 3 and the evaporation unit 2 and the fuel cell 1.

  During operation, the reformer 2A is heated in the heat insulating wall 19 so as to be suitable for the reforming reaction. During operation, the evaporation unit 2 is heated so that water can be heated to steam. When the fuel cell 1 is of the SOFC type, the anode exhaust gas discharged from the anode 10 side via the flow path 103 and the cathode exhaust gas discharged from the cathode 11 side via the flow path 104 burn in the combustion unit 105. The reforming unit 3 and the evaporation unit 2 are heated simultaneously.

  The fuel passage 6 supplies fuel from the fuel source 63 to the reformer 2 </ b> A, and includes a fuel pump 60 and a desulfurizer 62. A cathode fluid passage 70 for supplying cathode fluid (air) to the cathode 11 is connected to the cathode 11 of the fuel cell 1. The cathode fluid passage 70 is provided with a cathode pump 71 that functions as a water transport source for transporting the cathode fluid.

  As shown in FIG. 1, the case 5 has an intake port 50 and an exhaust port 51 communicating with outside air, and further has an upper chamber space 52 as a first chamber and a lower chamber space 53 as a second chamber. . The fuel cell 1 is housed together with the reforming unit 3 and the evaporation unit 2 in the upper side of the case 5, that is, in the upper chamber space 52. The lower chamber space 53 of the case 5 accommodates a tank 4 that stores liquid-phase water reformed by the reforming unit 3. The tank 4 is provided with a heating unit 40 having a heating function such as an electric heater. The heating unit 40 heats the water stored in the tank 4 and can be formed with an electric heater or the like. When the environmental temperature such as the outside air temperature is low, the water in the tank 4 is heated to a predetermined temperature (for example, 5 ° C., 10 ° C., 20 ° C.) or more by the heating unit 40 based on a command from the control unit 100. Freezing is suppressed. It is preferable that the water level in the tank 4 is basically substantially the same.

  As shown in FIG. 1, a water supply passage 8 that connects the outlet port 4p of the tank 4 on the lower chamber space 53 side and the inlet port 2i of the evaporator 2 on the upper chamber space 52 side is provided in the case 5 as a pipe. ing. As shown in FIG. 1, in the case 5, since the tank 4 is disposed below the evaporation unit 2, the water supply passage 8 extends along the vertical direction. The heating section 40 is not provided in the water supply passage 8. This is because freezing of the water supply passage 8 is suppressed by the freeze suppression process according to the present embodiment.

  The water supply passage 8 is a passage through which water accumulated in the tank 4 is supplied from the outlet port 4p of the tank 4 to the inlet port 2i of the evaporator 2 to the evaporator 2. The water supply passage 8 is provided with a pump 80 that functions as a water conveyance source for conveying water in the tank 4 to the evaporation unit 2. As the pump 80, a known pump having a good sealing property such as a gear pump can be adopted. The pump 80 has an electric motor 82 for driving it. The pump 80 has a high water sealing property. When water is present in the water supply passage 8 downstream from the discharge port 80p of the pump 80, the water is prevented from leaking upstream from the pump 80 over a long period of time. Therefore, when the operation of the fuel cell system is stopped, water is often present in the water supply passage 8 in the passage portion 8x downstream of the discharge port 80p of the pump 80. Such water tends to cause freezing in winter or in cold regions. The water supply passage 8 is communicated with the atmosphere via the evaporation unit 2, the reforming unit 3, the fuel cell 1, and the like.

  According to the present embodiment, the motor 82 that drives the pump 80 can rotate forward and backward. That is, the motor 82 is rotationally driven in the forward direction to transport the water in the tank 4 from the outlet port 4p toward the inlet port 2i of the evaporation unit 2, and is rotated in the reverse direction to rotate the water supply passage 8. Switching to a reverse mode in which water is returned from the outlet 4p into the tank 4 is possible. Therefore, the pump 80 having the motor 82 can be switched between a normal mode in which the water in the tank 4 is transported to the evaporation unit 2 and a reverse mode in which the water in the water supply passage 8 is returned to the tank 4. A control unit 100 is provided for controlling the motor 82 via a drive circuit. The motor 82 may be any motor that can rotate forward and backward, but a stepping motor is preferred. The control unit 100 controls the pump 80 via the motor 82. Further, the control unit 100 controls the pumps 71, 79, 60 via the motors of the pumps 71, 79, 60.

  When the pump 60 is driven at the time of starting the system, the fuel flows from the fuel passage 6 to the combustion portion 105 via the evaporation portion 2, the reforming portion 3, the anode fluid passage 73, the anode 10 of the fuel cell 1, and the flow passage 103. . Cathode fluid (air) flows to the combustion section 105 through the cathode fluid passage 70, the cathode 11, and the flow path 104 by the cathode pump 71. When the ignition unit 35 ignites in this state, combustion occurs in the combustion unit 105, and the reforming unit 3 and the evaporation unit 2 are heated. When the pump 80 is driven in the positive mode while the reforming unit 3 and the evaporation unit 2 are heated in this way, the water in the tank 4 flows from the outlet port 4p of the tank 4 toward the inlet port 2i of the evaporation unit 2. It is conveyed in the water supply passage 8 and heated by the evaporation unit 2 to be steam. The water vapor moves to the reforming unit 3 together with the fuel supplied from the fuel passage 6 (preferably in a gaseous state, but may be in a liquid phase in some cases). In the reforming unit 3, the fuel is reformed with water vapor to become an anode fluid (hydrogen-containing gas). The anode fluid is supplied to the anode 10 of the fuel cell 1 through the anode fluid passage 73. Further, the cathode fluid (oxygen-containing gas, air in the case 5) is supplied to the cathode 11 of the fuel cell 1 through the cathode fluid passage 70. Thereby, the fuel cell 1 generates electric power. The anode fluid off-gas discharged from the anode 10 and the cathode fluid off-gas discharged from the cathode 11 pass through the flow paths 103 and 104, reach the combustion section 105, and are combusted in the combustion section 105. The hot exhaust gas is discharged outside the case 5 through the exhaust gas passage 75.

  A heat exchanger 76 having a condensation function is provided in the exhaust gas passage 75. A hot water storage passage 78 and a hot water storage pump 79 connected to the hot water storage tank 77 are provided. The hot water storage passage 78 has an outward path 78a and a return path 78c. The low-temperature water in the hot water storage tank 77 is discharged from the discharge port 77p of the hot water storage tank 77 by the drive of the hot water storage pump 79, passes through the forward path 78a, reaches the heat exchanger 76, and is heated by the heat exchanger 76. The water heated by the heat exchanger 76 returns to the hot water storage tank 77 from the return port 77i through the return path 78c. In this way, the water in the hot water storage tank 77 becomes warm water. The water vapor contained in the exhaust gas is condensed in the heat exchanger 76 to become condensed water. The condensed water is supplied to the water purification unit 43 by gravity or the like through the condensed water passage 42 extending from the heat exchanger 76. Since the water purification unit 43 has a water purification agent 43a such as an ion exchange resin, impurities of condensed water are removed. The water from which impurities have been removed moves to the water tank 4 and is stored in the water tank 4. When the pump 80 is driven in the positive mode, the water in the water tank 4 is supplied to the high-temperature evaporation unit 2 through the water supply passage 8, converted into water vapor in the evaporation unit 2, and supplied to the reforming unit 3. 3 is consumed as a reforming reaction for reforming the fuel.

  Now, when the power generation operation of the fuel cell system is stopped, there is a possibility that freezing will occur in at least one of the water supply passage 8 and the pump 80 when the environmental temperature such as the outside air temperature becomes low in winter or in a cold region. There is a time. Thus, when there is a possibility of freezing, the control unit 100 executes a freezing suppression process in which the forward mode and the reverse mode of the pump 80 are alternately executed. In the positive mode, the motor 82 is driven to rotate in the forward direction, the pump 80 is driven in the forward direction, and the water in the tank 4 is transported toward the inlet port 2 i of the evaporation unit 2 in the water supply passage 8. In general, it is preferable that water is transported to just before the inlet port 2 i of the evaporation unit 2 but does not enter the evaporation unit 2. Here, the term “immediately before” refers to the inlet port 2i of the evaporation unit 2 when the relative length of the water supply passage 8 extending between the outlet port 4p of the tank 4 and the inlet port 2i of the evaporation unit 2 is 100. It means an arbitrary value from 0.5 to 10 toward the tank 4 as a starting point.

  On the other hand, in the reverse mode, the motor 82 is rotationally driven in the reverse direction, the pump 80 is driven in the reverse direction, and the water in the water supply passage 8 is returned to the tank 4. As a result, warm water (for example, higher than 2 ° C.) in the tank 4 heated by the heating unit 40 is reciprocated in the water supply passage 8. Thereby, the control part 100 can perform the freezing suppression process with respect to the water supply path 8 and the pump 80, and can suppress freezing in the water supply path 8 and the pump 80. FIG. Therefore, the heating part (not shown) for the water supply passage provided in the water supply passage 8 to prevent the water supply passage 8 from being frozen can be eliminated, the number of parts can be reduced, and the cost of the system can be reduced.

  In the reverse mode described above, the water remaining in the water supply passage 8 can be returned to the tank 4. For this reason, when dust or the like is present in the water supply passage 8, the dust or the like can be collected at the bottom of the tank 4, and the dust is prevented from being supplied to the reforming unit 3, thereby protecting the reforming catalyst and the like. Can increase sex. Further, when the system has been stopped for a long time, the quality of water remaining in the water supply passage 8 may be lowered. In this case, in the reverse mode, the water can be returned to the tank 4 and diluted with the water (pure water, condensed water) in the tank 4, and the protection of the reforming catalyst and the like of the reformer 3 can be ensured.

  A temperature sensor 57 for detecting the environmental temperature (generally the outside air temperature) is provided. Although the temperature sensor 57 is disposed in the vicinity of the intake port 50 in the lower chamber space 53 of the case 5, the temperature sensor 57 may be disposed outside the case 5 in some cases. The temperature signal detected by the temperature sensor 57 is input to the control unit 100. Therefore, the control unit 100 determines whether or not freezing may occur in at least one of the water supply passage 8 and the pump 80 and whether or not freezing has started, based on the temperature signal of the temperature sensor 57. Can be determined. When the environmental temperature detected by the temperature sensor 57 rises and the possibility of freezing is eliminated, the control unit stops the freezing suppression process. In this case, it is preferable to end in the reverse mode and to eliminate the water remaining in the water supply passage 8. This is because the environmental temperature may decrease again.

[Embodiment 2]
Since this embodiment basically has the same configuration and the same function and effect as those of the first embodiment, FIG. 1 is applied mutatis mutandis. Examples of the motor 82 for driving the pump 80 include a stepping motor capable of forward and reverse rotation and a DC motor capable of forward and reverse rotation. When ending the power generation operation of the fuel cell system, the control unit 100 rotates the motor 82 in the reverse direction to execute the reverse mode of the pump 80. In the reverse mode, the water remaining in the water supply passage 8 flows back through the water supply passage 8 toward the tank 4 and is returned to the tank 4. It is preferable that the control unit 100 drives the pump 80 in the reverse mode until the water in the water supply passage 8 becomes empty. In this case, the water in the pump 80 is also empty. Therefore, even when there is a possibility that the water supply passage 8 is frozen in winter or in a cold region, the water supply passage 8 and the pump 80 are not operated until the next power generation operation is started after the power generation operation of the system is completed. The risk of freezing is eliminated.

  When the power generation operation of the fuel cell system is stopped for a long period of time, immediately before the power generation operation is stopped, the control unit 100 reversely rotates the motor 82 to execute the reverse mode of the pump 80. When the pump 80 is in the reverse mode, the water remaining in the water supply passage 8 flows back through the water supply passage 8 and is returned to the tank 4. As a result, the water in the water supply passage 8 becomes empty. The water in the pump 80 is also empty. Therefore, even in the winter season or in a cold region, even if the period from the end of the power generation operation of the system to the start of the next power generation operation is long, the water supply passage 8 and the pump 80 may be frozen. It will be resolved.

  Also in the present embodiment, when the power generation operation of the fuel cell system is stopped in winter or in a cold region, freezing may occur in at least one of the water supply passage 8 and the pump 80. In such a case, in a state where the water in the tank 4 is warmed by the heating unit 40, the control unit 100 executes a freezing suppression process that alternately executes the forward mode and the reverse mode of the pump 80. As described above, in the positive mode, the water in the tank 4 is transported in the water supply passage 8 to just before the inlet port 2i of the evaporation unit 2. In the reverse mode, the water remaining in the water supply passage 8 flows back through the water supply passage 8 and is returned to the tank 4. In this way, when the fuel cell system is stopped at night or the like, when there is a risk of freezing in the water supply passage 8, warm water heated by the heating unit 40 in the tank 4 (for example, 5 ° C or higher, 10 ° C or higher) (Or 20 ° C. or higher), a freezing suppression process in which the water supply passage 8 is reciprocated with respect to the evaporation unit 2 is executed. Therefore, freezing in the water supply passage 8 and the pump 80 can be suppressed.

[Embodiment 3]
Since this embodiment basically has the same configuration and the same function and effect as those of the first embodiment, FIG. 1 is applied mutatis mutandis. The motor that drives the pump 80 is a stepping motor 82s that can rotate forward and backward. When the power generation operation of the fuel cell system is stopped in winter or in a cold region, when there is a risk of freezing in at least one of the water supply passage 8 and the water conveyance source, the control unit 100 is as described above. Execute freeze suppression processing. At the start of the freezing suppression process, first, the pump 80 is rotated in the reverse direction by rotating the stepping motor 82s in the reverse mode and rotating it backward for a predetermined time tc or a shorter time. As a result, the water remaining in the water supply passage 8 is emptied, and all of the water is returned into the tank 4 from the outlet port 4p. In this case, the water supply passage 8 is basically at atmospheric pressure.

  Thereafter, the control unit 100 rotates the pump 80 in the positive direction by rotating the stepping motor 82s in the positive mode for a predetermined time ta. In the positive mode, warm water in the tank 4 heated by the heating unit 40 flows from the outlet port 4p of the tank 4 toward the evaporation unit 2 through the water supply passage 8. And water is conveyed to just before the entrance port 2i of the evaporation part 2. FIG.

  Here, “immediately before the inlet port 2i of the evaporating unit 2” is displayed relative to the total length of the water supply passage 8 extending between the outlet port 4p of the tank 4 and the inlet port 2i of the evaporating unit 2 as 100. In this case, it means an arbitrary value within the range of 0.5 to 20 from the inlet port 2i of the evaporation unit 2 toward the tank 4 as a starting point. For example, it can be set to an arbitrary value within the range of 0.5 to 10. Since the water supply passage 8 is not provided with a heating section such as a heater for heating the water supply passage 8, the heat of the water in the water supply passage 8 is transmitted to the water supply passage 8, and the temperature of the water in the water supply passage 8 gradually decreases. It is preferable to raise the temperature again.

  Therefore, thereafter, the control unit 100 executes the reverse mode of the pump 80 for a predetermined time tc. In the reverse mode, since the stepping motor 82s and the pump 82 rotate in reverse, all the water present in the water supply passage 8 returns to the tank 4 and is reheated by the heating unit 40 or mixed with warm water in the tank 4. The temperature is raised again. In this case, the inside of the water supply passage 8 becomes empty, and the risk of freezing of residual water in the water supply passage 8 is suppressed.

  As described above, according to the present embodiment, at the start of the freezing suppression process, the control unit 100 first executes the reverse mode of the pump 80 to empty the water supply passage 8. Thereafter, the control unit 100 causes the pump 80 to alternately execute the forward mode (drive time: ta) and the reverse mode (drive time: tc). As a result, warm water (for example, 5 ° C. or more) heated by the heating unit 40 in the tank 4 is reciprocated with respect to the evaporation unit 2 in the water supply passage 8. In this way, the control unit 100 executes the freezing suppression process and suppresses freezing in the water supply passage 8 and the pump 80. In addition, it is preferable to make the emitted-heat amount per unit time of the heating part 40 increase, so that environmental temperature, such as external temperature, is low.

[Embodiment 4]
Since this embodiment basically has the same configuration and the same function and effect as those of the first embodiment, FIG. 1 is applied mutatis mutandis. At the start of the freezing suppression process, the control unit 100 preferably first rotates the pump 80 in the reverse direction by rotating the stepping motor 82s in the reverse mode. As a result, the water remaining in the water supply passage 8 is emptied and returned from the outlet port 4p of the tank 4 into the tank 4. In this case, the controller 100 feeds the reverse rotation drive pulse having the total number Nc of reverse mode pulses to the stepping motor 82s. As a result of such a reverse mode, all of the water remaining in the water supply passage 8 basically returns to the tank 4 and is heated again in the tank 4. In this case, since the inside of the water supply passage 8 and the pump 80 is empty, freezing of the water supply passage 8 and the pump 80 is suppressed. Here, the total number Nc of pulses for the reverse mode fed to the stepping motor 82s is basically the same as the water supply passage 8 in the water supply passage 8 until all the water supplied up to just before the inlet port 2i of the evaporation section 2 is supplied. The interior is set back to the tank 4. In this case, as described above, the passage length of the water supply passage 8 and the passage volume of the water supply passage 8 are known. For this reason, the total pulse number Nc for the reverse mode is set so that all of the water supplied up to the position immediately before the inlet port 2 i of the evaporator 2 in the water supply passage 8 returns to the tank 4.

  As described above, after the water in the water supply passage 8 is emptied, the control unit 100 causes the pump 80 to execute the normal mode. In this case, the control unit 100 supplies power to the stepping motor 82s with the positive rotation drive pulse having the total pulse number Na for the positive mode. In the positive mode, the stepping motor 82s corresponding to the total pulse number Na rotates in the positive direction, and the pump 80 is driven in the positive direction. The total number Na of pulses for the positive mode supplied to the stepping motor 82s is basically supplied from the state where the water supply passage 8 is empty (reference state) to the time when the pump 80 supplies water to just before the inlet port 2i of the evaporation unit 2. This corresponds to the amount of water that is conveyed in the forward direction in the passage 8. In this case, since the passage length of the water supply passage 8 and the passage volume of the water supply passage 8 are known, the total number Na of pulses in the positive mode is basically that the water evaporates in the empty water supply passage 8. It is set so as to reach the position immediately before the second inlet port 2i.

  Thus, when the stepping motor 82s and the pump 80 are in the positive mode, the warm water in the tank 4 heated by the heating unit 40 flows from the outlet port 4p of the tank 4 toward the evaporation unit 2 through the water supply passage 8 and evaporates. It is transported to just before the entrance port 2i of the section 2. This is because water does not enter the evaporating unit 2 in the freezing suppression process. Since the heating section for heating the water supply passage 8 is not provided, the temperature of the water in the water supply passage 8 gradually decreases. Note that Na = Nc and Na≈Nc. However, it is not limited to this.

  After performing the normal mode, if there is a possibility of freezing, the control unit 100 causes the stepping motor 82s and the pump 80 to execute the reverse mode. In this case, as described above, the control unit 100 supplies the reverse rotation drive pulse having the total pulse number Nc to the stepping motor 82s. In the reverse mode, all the water present in the water supply passage 8 basically returns to the tank 4 and is heated again by the heating unit 40. In this case, the inside of the water supply passage 8 is in an empty state, and basically becomes an atmospheric pressure state.

  As described above, also in the present embodiment, at the start of the freezing suppression process, the control unit 100 first executes the reverse mode of the pump 80, and thereafter, the normal mode (total number of pulses: Na) and the reverse mode (pulse number) of the pump 80. The total number: Nc) is alternately executed. Thereafter, warm water (for example, higher than 2 ° C.) heated by the heating unit 40 in the tank 4 is reciprocated with respect to the evaporation unit 2 in the water supply passage 8. In this way, the control unit 100 executes the freezing suppression process and suppresses freezing in the water supply passage 8 and the pump 80. In addition, it is preferable to make the emitted-heat amount per unit time of the heating part 40 increase, so that environmental temperature, such as external temperature, is low.

[Embodiment 5]
Since this embodiment basically has the same configuration and the same function and effect as those of the first embodiment, FIG. 1 is applied mutatis mutandis. As described above, the temperature sensor 57 for detecting the environmental temperature (outside air temperature) is provided in the vicinity of the intake port 50. When the power generation operation of the fuel cell system is stopped, the control unit 100 detects that the temperature T detected by the temperature sensor 57 is equal to or lower than the first threshold temperature T1 (T1 ≦ 5 ° C.) and the second threshold temperature T2 (T2). When higher than <T1), it is determined that there is a risk of freezing, and the reverse mode in which water is returned to the tank 4 is prioritized over the normal mode in which water is supplied. That is, the controller 100 drives the motor 82 and the pump 80 in the reverse mode to reduce or empty the water in the water supply passage 8 and return it to the tank 4. In this case, the control unit 100 has not yet repeatedly moved the warm water in the tank 4 back and forth in the water supply passage 8. That is, the forward mode and the reverse mode are not repeated a plurality of times alternately. Therefore, the electrical energy consumed by the pump 80 is saved. The heating unit 40 of the tank 4 may be turned on or turned off. By turning it off, the amount of heat generation can be suppressed. Note that the first threshold temperature T1 described above means a temperature at which the possibility of freezing in the water supply passage 8 or the pump 80 in the case 5 is not so high. Examples of T1 include 3 ° C. and 5 ° C. However, it is not limited to these.

  On the other hand, when the detected temperature T of the temperature sensor 57 is equal to or lower than the second threshold temperature T2 (T2 <T1 ≦ 2 ° C.), the control unit 100 determines that there is a high possibility that the water supply passage 8 is frozen. . In this case, the control unit 100 causes the forward mode and the reverse mode of the stepping motor 82s to alternately execute, that is, causes the pump 80 to alternately execute the normal mode and the reverse mode to execute the freeze suppression process. Even in this case, it is preferable to prioritize the reverse mode over the normal mode. As a result of the freeze suppression process, warm water in the tank 4 heated by the heating unit 40 is reciprocated in the water supply passage 8 to suppress freezing of the water supply passage 8 and the pump 80. Examples of the second threshold temperature T2 include −2 ° C., −5 ° C., and −15 ° C., but are not limited thereto.

  FIG. 2 shows an example of a flowchart executed by the CPU of the control unit 100 in the freeze suppression process. First, the control unit 100 reads signals from various sensors such as the temperature sensor 57 and various devices (step S102). If the fuel cell system is currently operating (power generation operation and start-up operation) (NO in step S104), there is substantially no risk of freezing of the water supply passage 8, and thus the freezing suppression process is not executed (step S130).

  On the other hand, when the operation (power generation operation and start-up operation) of the fuel cell system is stopped (YES in step S104), there is a possibility that freezing may occur in the winter or in a cold region. Therefore, the control unit 100 compares the detected temperature T detected by the temperature sensor 57 with the second threshold temperature T2 (step S106). When the temperature T detected by the temperature sensor 57 is equal to or lower than the second threshold temperature T2 (for example, −2 ° C.) (T ≦ T2, YES in step S106), there is a high possibility of freezing. For this reason, the control unit 100 gives priority to the reverse mode over the normal mode, rotates the motor 82 in reverse, and executes the reverse mode of the pump 80 for a predetermined drive time tc (step S108). Return all to the tank 4. Thereafter, the control unit 100 waits for a time Δte while the pump 80 is stopped (step S110). Δte can be set in consideration of, for example, the time required for switching the rotation direction of the motor 82, the time during which the water returned to the tank 4 is mixed with the hot water in the tank 4 and heated. preferable.

  Next, the control unit 100 rotates the motor 82 in the forward direction and executes the positive mode of the pump 80 for a predetermined drive time ta (step S112). Thereafter, the control unit 100 waits for a time Δtf while the pump 80 is stopped (step S114). Δtf is preferably set in consideration of the time during which warm water supplied to the water supply passage 8 (preferably 5 ° C. or more) is transferred to the inner wall surface of the water supply passage 8. Thereafter, the control unit 100 performs another process (step S116), and then returns to step S102.

  According to the present embodiment, when the freeze suppression process is executed, when the detected temperature T of the temperature sensor 57 is equal to or lower than the first threshold temperature T1 and higher than T2 (T2 <T ≦ T1, step S120). (YES), since there is a considerable possibility of freezing, the controller 100 reversely rotates the motor 82 to execute the reverse mode of the pump 80 (step S108). As a result, all of the water in the water supply passage 8 is returned to the tank 4. When the detected temperature T of the temperature sensor 57 is higher than the first threshold temperature T1 (for example, 2 ° C.) (T> T1, NO in step S120), it is considered that there is no fear of freezing of the water supply passage 8, and therefore control is performed. The unit 100 turns off the heating unit 40 and does not execute the freeze suppression process (step S130).

  In addition, according to this embodiment, when there is a possibility of freezing, it is preferable to increase the heat generation amount per unit time of the heating unit 40 as the environmental temperature such as the outside air temperature is lower. Further, when there is a possibility of freezing, the waiting time Δte, Δtf of the stepping motor 82e is relatively shortened as the environmental temperature such as the outside air temperature is lower as compared with the case where the environmental temperature is higher. The frequency per unit time in which warm water is reciprocated in the water supply passage 8 can be relatively increased.

[Embodiment 6]
Since this embodiment basically has the same configuration and the same function and effect as those of the first embodiment, FIG. 1 is applied mutatis mutandis. The motor is a stepping motor 82s. As shown in FIG. 1, a water sensor 87 is provided for detecting the presence of water in the passage portion 8 x between the inlet port 2 i of the evaporator 2 and the discharge port 80 p of the pump 80 in the water supply passage 8. . Specifically, the water sensor 87 detects the presence of water immediately before the inlet port 2 i of the evaporation unit 2 in the water supply passage 8. At the start of the freezing suppression process, the control unit 100 first rotates the pump 80 in the reverse direction by rotating the stepping motor 82s in the reverse mode and rotating it backward by the total number of pulses Nc. As a result, the water remaining in the water supply passage 8 is emptied, and all of the water in the water supply passage 8 is returned from the outlet port 4p of the tank 4 into the tank 4.

  Thereafter, the control unit 100 causes the pump 80 to execute the normal mode. In this case, the control unit 100 supplies power to the stepping motor 82s with the forward rotation driving pulse having the total number Na of pulses. The controller 100 drives the stepping motor 82s corresponding to the total number Na of pulses in the forward direction, and thus drives the pump 80 in the forward direction. The total number Na of pulses in the positive mode basically corresponds to the amount of water that the pump 80 conveys in the water supply passage 8 in the positive direction toward the evaporation unit 2 from the empty water supply passage 8. In this case, the length of the water supply passage 8 and the passage volume of the water supply passage 8 are known. Therefore, the total pulse number Na is set so that the water reaches the position immediately before the inlet port 2i of the evaporation unit 2 in the water supply passage 8. Thus, when the stepping motor 82s and the pump 80 are in the positive mode, the warm water in the tank 4 heated by the heating unit 40 flows from the outlet port 4p of the tank 4 toward the evaporation unit 2 through the water supply passage 8 and evaporates. It is transported to just before the entrance port 2i of the section 2.

  Thereafter, the control unit 100 reversely rotates the stepping motor 82s to execute the reverse mode of the pump 80. In this case, the control unit 100 supplies power to the stepping motor 82s with the reverse rotation drive pulses having the total pulse number Nc. In the reverse mode, all of the water present in the water supply passage 8 basically returns to the tank 4 and is heated again by the heating unit 40. In this case, the inside of the water supply passage 8 is empty. The total number Nc of pulses is basically set so as to correspond to the amount of water that transports the water supplied to the water supply passage 8 toward the tank 4 in the reverse direction in the water supply passage 8. In this case, since the passage length of the water supply passage 8 and the passage volume of the water supply passage 8 are known as described above, the total pulse number Nc is basically just before the inlet port 2i of the evaporation unit 2 in the water supply passage 8. It is set so that all of the water supplied up to the position is returned to the tank 4.

  As described above, also in the present embodiment, at the start of the freezing suppression process, the control unit 100 first preferentially executes the reverse mode of the pump 80, and then intermittently alternates between the forward mode and the reverse mode of the pump 80. To run. As a result, warm water (for example, higher than 2 ° C.) heated by the heating unit 40 in the tank 4 is reciprocated with respect to the evaporation unit 2 in the water supply passage 8. In this way, the control unit 100 executes the freezing suppression process and suppresses freezing in the water supply passage 8 and the pump 80.

  As a control parameter, the driving time ta of the stepping motor 82s in the positive mode may be employed instead of the total pulse number Na in the positive mode. The drive time ta is basically determined from the state where the water supply passage 8 is empty, and the pump 80 transports water in the water supply passage 8 in the forward direction toward the evaporation unit 2 to supply water to the water sensor 87 (inlet of the evaporation unit 2). This corresponds to the time required to reach the port 2i. As the control parameter, the driving time tc of the stepping motor 82s in the reverse mode may be employed instead of the total pulse number Nc in the reverse mode. The driving time tc in the reverse mode basically corresponds to a time for returning all the almost full water in the water supply passage 8 to the tank 4.

  In the present embodiment, the water sensor 87 can detect the amount of water supplied to the water supply passage 8. In this case, in the positive mode, the water sensor 87 is used even though the total number of pulses supplied to the stepping motor 82s does not reach Na or the driving time of the stepping motor 82s is shorter than ta. May detect the presence of water. In this case, the inner wall surface of the water supply passage 8 becomes narrower due to the start of freezing or the like, and the cross-sectional area of the water supply passage 8 is already reduced. It is estimated that the height position can be reached.

  Therefore, the control unit 100 gives priority to the water detection signal of the water sensor 87 over the total number Na of pulses fed to the stepping motor 82s or over the drive time ta of the stepping motor 82s. Therefore, when the water sensor 87 detects and turns on water even though the total pulse number Na or the driving time ta (which can include a margin value) has not been reached, the controller 100 uses this as a trigger signal, The forward rotation of the stepping motor 82s is stopped, and the positive mode in which the water in the tank 4 is supplied to the water supply passage 8 is stopped. Thereafter, the control unit 100 executes the reverse mode of the pump 80 and returns the water in the water supply passage 8 into the tank 4. In this case, although water can be passed through the water supply passage 8, it is estimated that freezing has started on the inner wall surface of the water supply passage 8. Therefore, the control unit 100 increases the amount of heat generated by the heating unit 40 of the tank 4 by ΔW and further increases the temperature of the water stored in the tank 4. Therefore, when the control unit 100 next executes the normal mode, water having a higher temperature in the tank 4 is supplied to the water supply passage 8, so that the water supply passage 8 is easily thawed.

  Even when the control unit 100 executes the next positive mode, the total number of pulses supplied to the stepping motor 82s does not reach Na or the driving time of the stepping motor 82s is shorter than ta. Nevertheless, the water sensor 87 may detect water. In this case, as described above, freezing is started, the inner wall surface of the water supply passage 8 is narrowed by freezing or the like, and it is determined that the flow passage cross-sectional area of the water supply passage 8 is small.

  Therefore, the control unit 100 gives priority to the water detection signal of the water sensor 87 over the total number Na of pulses fed to the stepping motor 82s or the driving time ta of the stepping motor 82s, and when the water sensor 87 detects water, As a trigger signal, the forward rotation of the stepping motor 82s is stopped, and the positive mode in which the water in the tank 4 is supplied to the water supply passage 8 is stopped. Therefore, supply of water to the evaporation unit 2 is suppressed. Thereafter, when a predetermined time has elapsed or immediately, the control unit 100 executes the reverse mode of the pump 80 and returns the water in the water supply passage 8 into the tank 4. In this case, in the previous mode, it is determined that freezing still remains on the inner wall surface of the water supply passage 8 even though the amount of heat generated by the heating unit 40 of the tank 4 is increased. Therefore, the control unit 100 again increases the amount of heat generated by the heating unit 40 of the tank 4 by ΔW, and further increases the temperature of the water stored in the tank 4. For this reason, when the control unit 100 executes the next positive mode, water having a higher temperature in the tank 4 is supplied to the water supply passage 8, so that the water supply passage 8 is easily frozen.

  Thus, even though the total number of pulses supplied to the stepping motor 82s in the positive mode has not reached Na or the driving time of the stepping motor 82s is shorter than ta, the water sensor 87 is Is detected, it is determined that the water supply passage 8 is frozen and the cross-sectional area of the flow path is small. For this reason, the control part 100 can gradually increase the calorific value of the heating part 40 of the tank 4 by ΔW each time to promote freezing suppression and thawing. In addition, when the emitted-heat amount of the heating part 40 becomes excess, it is preferable not to make it increase any more.

  FIG. 3 shows an example of the positive mode executed by the CPU of the control unit 100 in the positive mode. First, the control unit 100 sets the total number of pulses supplied to the stepping motor 82s in the positive mode as Na, or sets the driving time of the stepping motor 82s as ta (step S202). Next, a command for driving the stepping motor 82s is output as the total pulse number Na or the driving time ta of the stepping motor 82s (step S204). Here, the total number of pulses Na input to the stepping motor 82s and the driving time ta of the stepping motor 82s are such that when the water in the water supply passage 8 is empty, the stepping motor 82s rotates forward and the pump 80 is driven in the positive mode. At this time, the water flowing toward the evaporation unit 2 through the water supply passage 8 is set to reach the height position of the water sensor 87 (position just before the evaporation unit 2). Therefore, when the water sensor 87 detects water and turns on before the total number of pulses supplied to the stepping motor 82s reaches Na or before the driving time of the stepping motor 82s reaches ta, the above-described operation is performed. Thus, it is determined that the inner wall surface of the water supply passage 8 is frozen and the flow passage cross-sectional area of the water supply passage 8 is reduced. As described above, according to the present embodiment, it is possible to determine whether or not the water supply passage 8 is frozen when the freeze suppression process is performed.

  Therefore, the control unit 100 determines whether or not the total pulse number Na or the driving time ta of the stepping motor 82s has ended (step S206). If completed (YES in step S206), the process returns to the main routine. If not completed (NO in step S206), the signal from the water sensor 87 is read (step S208). If the water sensor 87 is outputting an ON signal (YES in step S210), although the water has reached the height position of the water sensor 87 in the water supply passage 8, the inner wall surface of the water supply passage 8 is frozen and the water supply passage 8 is frozen. It is determined that the flow path cross-sectional area is small. Therefore, the control unit 100 stops the forward rotation of the stepping motor 82s and ends the normal mode (step S212), increases the heat generation amount of the heating unit 40 by ΔW from the initial stage (step S214), and alerts the freezing alarm signal. The controller 102 outputs the data (step S216) and returns to the main routine. The control unit 100 preferably increases ΔW as the environmental temperature such as the outside air temperature is lower. However, it is not limited to this.

[Embodiment 7]
Since this embodiment basically has the same configuration and the same function and effect as those of the first embodiment, FIG. 1 is applied mutatis mutandis. Also in this embodiment, when the normal mode is executed, the water sensor 87 detects that the water supplied to the water supply passage 8 reaches the evaporator 2 immediately before the inlet port 2i. In this case, when the normal mode is executed, the feed water passage 8 is empty (reference state), the total number of pulses supplied to the stepping motor 82s reaches Na, or the stepping motor 82s is driven. Even though the time reaches ta, the water sensor 87 may not detect water. In this case, water leakage from the water supply passage 8 occurs, and it is expected that water has not reached the height position of the water sensor 87. Here, in the positive mode, when the total number of pulses fed to the stepping motor 82s reaches Na + ΔNx (positive value) or when the driving time of the stepping motor 82s reaches ta + Δtx (positive value), the water sensor 87 Suppose it is turned on. In this case, it is determined that water does not easily reach the water sensor 87 because water leakage has occurred in the water supply passage 8.

  When such a phenomenon is recognized continuously for a prescribed number of times CA (for example, three times), there is a high probability that a water leak has occurred in the water supply passage 8. For this reason, the control unit 100 executes the reverse mode and returns all the water in the water supply passage 8 to the tank 4, then stops the freeze suppression process and issues an alarm for notifying the water leakage in the water supply passage 8. Output to the device 102. When the specified number of times CA is not reached, the control unit 100 advances the freeze suppression process.

  FIG. 4 shows an example of the positive mode executed by the CPU of the control unit 100. First, the control unit 100 sets the total number of pulses supplied to the stepping motor 82s as Na or sets the driving time of the stepping motor 82s as ta (step S302). Next, a command for driving the stepping motor 82s is output as the total pulse number Na or the driving time ta of the stepping motor 82s (step S304). Here, the total number of pulses Na and the driving time ta of the stepping motor 82s are such that when the water in the water supply passage 8 is empty, when the stepping motor 82s rotates forward and the pump 80 is driven in the positive mode, the water is a water sensor. It is set in advance so as to reach the height position of 87. Therefore, when the water sensor 87 is turned on when the total number of pulses fed to the stepping motor 82s is Na that is greater than Na by a predetermined value or when the driving time of the stepping motor 82s is greater than ta by a predetermined value, It is determined that there is a possibility that water leakage has occurred in the passage 8.

  Thus, during the execution of the positive mode, the control unit 100 reads the signal from the water sensor 87 (step S306). If the water sensor 87 is outputting an ON signal (YES in step S308), since the water has reached the height position of the water sensor 87 in the water supply passage 8, the control unit 100 stops the stepping motor 82s ( Step S310). Next, the controller 100 counts the total number of pulses Np from the start time of the positive mode to the current time (on time of the water sensor 87), or from the start time of the positive mode to the current time (on time of the water sensor 87). The driving time tp is obtained (step S312). The control unit 100 determines whether the total number of pulses Np up to the present is larger than the total number Na of pulses for the positive mode or whether the driving time tp up to the present is longer than the driving time ta for the positive mode ( Step S314). When the current total pulse number Np is larger than the positive mode pulse total number Na, or when the current drive time tp is longer than the positive mode drive time ta (YES in step S314), water leaks in the water supply passage 6. There is a risk. For this reason, the control unit 100 increases the counter value C for water leakage by 1 (step S316). Next, when the counter value C exceeds a threshold value CA for water leakage (for example, an arbitrary value of 3 or more) (YES in step S318), an alarm for water leakage in the water supply passage 8 is output to the alarm device 102 ( In step S320, the process returns to the main routine. As described above, according to the present embodiment, it is possible to determine the water leakage of the water supply passage 8 when performing the freeze suppression process.

[Embodiment 8]
Since this embodiment basically has the same configuration and the same function and effect as those of the first embodiment, FIG. 1 is applied mutatis mutandis. A pressure sensor 87 p is provided as a water sensor for detecting the presence of water in the passage portion 8 m between the evaporation section 2 and the pump 80 in the water supply passage 8. The pressure sensor 87p has a function of detecting the water head pressure based on the water present in the passage portion 8m from the pressure sensor 87p to the inlet port 2i of the evaporation unit 2 in the water supply passage 8. The pressure sensor 87p is provided in a passage portion extending in the vertical direction in the water supply passage 8 so as to satisfactorily detect the water head pressure. Based on the signal of the pressure sensor 87p, the amount of water present in the passage portion 8m from the height position of the pressure sensor 87p to the inlet port 2i of the evaporation unit 2 in the water supply passage 8 is detected.

  For example, when the output value of the pressure sensor 87p is equal to or less than a predetermined value (for example, 0.1 kPa), the control unit 100 determines that there is no water in the water supply passage 8 above the pressure sensor 87p. In the positive mode, the control unit 100 obtains a time t1 when the output of the pressure sensor 87p exceeds a predetermined value (for example, 0.1 kPa) to the high pressure side from a pressure value lower than the predetermined value (for example, 0.1 kPa). Time t1 means the time at which water reaches the same height position as the sensor detection part of the pressure sensor 87p (corresponding to the height position immediately before the inlet port 2i of the evaporation part 2) in the water supply passage 8. Therefore, the controller 100 can return all the water in the water supply passage 8 to the tank 4 by driving the motor 82 and the pump 80 in the reverse mode for the drive time tc from the time t1.

[Embodiment 9]
Since this embodiment basically has the same configuration and the same function and effect as those of the first embodiment, FIG. 1 is applied mutatis mutandis. As described above, the rotation speed of the motor 82 (stepping motor 82s) in the freeze suppression process can be set to Va <Vc when the rotation speed in the normal mode is Va and the rotation speed in the reverse mode is Vc. In this case, the heat of the water held in the water supply passage 8 is taken away by the inner wall surface of the water supply passage 8. Therefore, the water in the water supply passage 8 is gradually cooled. Therefore, the control unit 100 can quickly return the water held in the water supply passage 8 to the tank 4 and quickly raise the temperature in the tank 4.

  [Others] The present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications without departing from the scope of the invention. The heating unit 40 is provided in the tank 4, but is not limited thereto, and may be provided in the condensed water passage 42. The fuel cell 1 may be a polymer electrolyte fuel cell (operating temperature: for example, 70 to 100 ° C.) called PEFC or a phosphoric acid fuel cell called PAFC depending on the case, and an electrolyte membrane containing phosphoric acid. May be used, or other types of fuel cells may be used. In short, any fuel cell system may be used as long as the fuel cell system has an evaporating section that forms, from raw material water, water vapor that reforms vapor phase or liquid phase fuel.

  The following technical idea can be understood from the above description.

  [Additional Item 1] A fuel cell that generates electricity by supplying an anode fluid and a cathode fluid, an evaporation unit that evaporates water to generate water vapor, and reforms fuel using the water vapor generated in the evaporation unit to improve the anode A reforming unit that forms a fluid, a tank that stores water supplied to the evaporation unit, a heating unit that heats water supplied to the tank or water stored in the tank, and the tank and the evaporation unit communicate with each other. A fuel cell system comprising: a water supply passage for supplying water in the tank to the evaporation section; a water transfer source provided in the water supply path for transferring water in the tank to the evaporation section; and a control section for controlling the water transfer source. In this case, when the temperature detected by the temperature sensor is higher than the first threshold temperature T1, the control unit drives the water conveyance source in the reverse mode to reduce or empty the raw material water in the water supply passage. Can be brought back in. In addition, when the temperature detected by the temperature sensor is equal to or lower than the second threshold temperature T2 (T2 <T1), it is determined that there is a possibility of freezing, so the forward mode and the reverse mode of the water conveyance source are alternately executed. It is preferable to execute a freezing suppression process in which the raw water in the tank is reciprocated in the water supply passage to suppress freezing of the water supply passage. Moreover, it is preferable that the water sensor for detecting presence of the raw material water in the channel | path part between an evaporation part and a water conveyance source among water supply paths is provided. In this case, it is preferable that the control unit switches between the normal mode and the reverse mode of the water conveyance source based on a signal from the water sensor when the water conveyance source is driven in the freeze suppression process.

  1 is a fuel cell, 10 is an anode, 11 is a cathode, 2A is a reformer, 2 is an evaporation unit, 3 is a reforming unit, 4 is a tank, 40 is a heating unit, 5 is a case, 57 is a temperature sensor, 6 is Fuel passage, 70 is cathode fluid passage, 73 is anode fluid passage, 75 is exhaust gas passage, 77 is hot water storage tank, 8 is water supply passage, 8m is passage portion, 80 is pump (water conveyance source), 82 is motor, 82s is A stepping motor (motor), 87 is a water sensor, 87p is a pressure sensor (water sensor), and 100 is a control unit.

Claims (5)

A fuel cell that is supplied with an anode fluid and a cathode fluid to generate electricity, an evaporation unit that evaporates raw water to generate water vapor, and reforms fuel using the water vapor generated in the evaporation unit to produce an anode fluid A reforming unit to be formed, a tank for storing raw water supplied to the evaporation unit, a heating unit for heating the raw water supplied to the tank or the raw water stored in the tank, and the tank And a water supply passage for communicating raw water in the tank to the evaporation portion by communicating with the evaporation portion, and transporting water in the tank toward the inlet port of the evaporation portion by forward rotation provided in the water supply passage A water conveyance source that can be switched to a normal mode for causing the water supply passage water to return to the tank by reverse rotation, a control unit that controls the water conveyance source, and detecting an environmental temperature. And comprising a temperature sensor because,
When the control unit is likely to freeze in at least one of the water supply passage and the water conveyance source, or when freezing is started, the normal mode and the reverse mode of the water conveyance source Are alternately executed, and the fuel cell system executes a freezing suppression process for suppressing the freezing of the water supply passage by reciprocating the raw water in the tank in the water supply passage.   In Claim 1, the said control part gives priority to a reverse mode over a normal mode at the time of the start of the said freeze suppression process, and drives the said water conveyance source as the said reverse mode, and makes raw material water in the said water supply channel | path A fuel cell system that performs a return process that is emptied and returned to the tank. 3. The control unit according to claim 1, wherein when the temperature detected by the temperature sensor is equal to or lower than a first threshold temperature T <b> 1 (T <b> 1 ≦ 5 ° C.), the control unit drives the water conveyance source as the reverse mode. The raw water in the water supply passage is reduced or emptied and returned to the tank,
When the temperature detected by the temperature sensor is equal to or lower than a second threshold temperature T2 (T2 <T1), it is determined that there is a risk of freezing, and the forward mode and the reverse mode of the water conveyance source are alternately executed. A fuel cell system that performs the freeze suppression process for reciprocating the raw water in the tank in the water supply passage to suppress freezing of the water supply passage.   In any one of Claims 1-3, the water sensor for detecting presence of the raw material water in the channel | path part between the said evaporation part and the said water conveyance source is provided in the said water supply path, In the freezing suppression process, the control unit stops the normal mode of the water conveyance source based on a signal from the water sensor when the water conveyance source is driven.   In any one of Claims 1-4, when the said control part determines with freezing having generate | occur | produced in the said water supply channel | path, it repeats the said normal mode and reverse mode, and is performed in multiple times, The said normal mode The fuel cell system which raises the temperature of the raw material water in the tank by increasing the heat generation amount per unit time of the heating unit stepwise or continuously from the initial stage as the number of executions increases.

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